As energy costs continuously rise, fuel economy has become an increasingly important consideration in vehicle design. For example, ongoing design efforts have been directed towards reducing vehicle drag. As is generally understood, as the drag on a vehicle increases, the amount of fuel needed to move the vehicle also increases. For instance, it has been stated that for a vehicle traveling at 70 mph, about 65% of the total fuel consumption of the vehicle's engine is used to overcome drag. Therefore, even a small reduction in the drag experienced by a vehicle traveling at highway speeds can result in a significant improvement in fuel economy.
For instance, heavy-duty vehicles, such as tractor-trailers (also known as semi tractors, tractors, class 8 long haul trucks, transfer trucks, 18-wheelers, semis, etc.) have a tall and wide box-shaped profile that creates a significant amount of drag compared to other common road vehicles (e.g., cars and light trucks). For instance, Table I lists the common drag coefficients for road vehicles.
TABLE IType of VehicleDrag Coefficient (Cd)Low Drag Production Car0.26Typical Sedan 0.3-0.35Sport Utility Vehicle0.4-0.5Pick-up Truck0.4-0.5Tractor trailers0.59-0.63
In addition, heavy duty vehicles are typically equipped with large side-view mirror assemblies that extend outboard of the vehicle's body structure. Unfortunately, because such side mirror assemblies increase the lateral profile of the vehicle, the assemblies increase the drag on the vehicle, thereby resulting in a corresponding reduction in fuel economy. For example, FIG. 1 illustrates a partial, top view of a vehicle 10 having a conventional side mirror assembly 12 installed thereon. As shown, the mirror assembly 12 includes a mirror 14 (shown in dashed lines) and a mirror housing 16 configured to support the mirror 14 at a suitable position for allowing the driver to obtain a rearward view along the side of the vehicle 10. Due to the width of the mirror 14 and the angle that the mirror 14 must be oriented relative to the vehicle 10 to provide the driver a suitable rearwardly-directed viewing angle, the mirror housing 16 defines a relatively large effective width 18 within the airflow flowing along the side of the vehicle 10. As such, the illustrated mirror assembly 12 typically results in a substantial increase in the vehicle drag.
As a solution to the additional drag resulting from conventional side-view mirror assemblies, attempts have been made to eliminate the necessity of such mirror assemblies. For example, vision systems have been developed that utilize one or more cameras and associated display monitors to provide rear and/or side views of the vehicle to the driver. Specifically, cameras are typically mounted at one or more locations on the vehicle (e.g., on the side and/or at the back of the vehicle) and are electronically coupled to a display monitor(s) installed on and/or within a component(s) of the vehicle (e.g., within the dashboard, within the side-view mirror and/or at any other suitable location). The driver may then look at the display monitor(s) to gain access to side and/or rear views of the vehicle without necessity of relying on mirrors. However, current regulations require that vehicles include physical side-view mirrors that can be used by the driver in the event that the vision system fails. Accordingly, even for vehicles with sophisticated visions systems, side-view mirror assemblies must still be available for back-up purposes.
Thus, a need exists for improved aerodynamic mirror assemblies that are designed to provide drag reduction. Methods relating to the utilization of such mirror assemblies would also be beneficial. Moreover, retrofit kits for incorporating such mirror assemblies into vehicles would also be beneficial.